The present invention relates to disc drive data storage systems and, more particularly, to a disc head slider for communicating with a recording medium within a disc drive.
Disc drives use rigid discs, which are coated with a magnetizable medium for storage of digital information in a plurality of circular, concentric data tracks. The discs are mounted on a spindle motor, which causes the discs to spin and the surfaces of the discs to pass under respective hydrodynamic (e.g., air) bearing disc head sliders. The sliders carry transducers, which write information to and read information from the disc surfaces.
An actuator mechanism moves the sliders from track-to-track across the surfaces of the discs under control of electronic circuitry. The actuator mechanism includes a track accessing arm and a suspension for each head gimbal assembly. The suspension includes a load beam and a gimbal. The load beam provides a load force which forces the slider toward the disc surface. The gimbal is positioned between the slider and the load beam, or is integrated in the load beam, to provide a compliant connection that allows the slider to pitch and roll and assume an orientation relative to the disc that balances the hydrodynamic forces that support the slider.
The slider includes a bearing surface, which faces the disc surface. As the disc rotates, the disc drags air under the slider and along the bearing surface in a direction approximately parallel to the tangential velocity of the disc. As the air passes beneath the bearing surface, air compression along the air flow path causes the air pressure between the disc and the bearing surface to increase, which creates a hydrodynamic lifting force that counteracts the load force and causes the slider to lift and fly above or in close proximity to the disc surface.
One type of slider is a xe2x80x9cself-loadingxe2x80x9d air bearing slider, which includes a leading taper (or stepped-taper), a pair of raised rail features, a cavity dam and a subambient pressure cavity. The leading taper is typically lapped or etched onto the end of the slider that is opposite to the recording head. The leading taper pressurizes the air as the air is dragged under the slider by the disc surface. The trailing edge of the cavity dam provides an expansion path for the air to de-pressurize as it is dragged into the sub-ambient pressure cavity by the disc velocity. The expanded air in the cavity provides a self-loading force which forces the slider toward the disc surface. The counteraction between positive pressure developed along the rail features, the preload force provided by the suspension and the self-loading force provides the air bearing with a high vertical stiffness.
The physical separation between the slider and the disc surface at the recording head is an important parameter to disc drive performance. It is desired to minimize variation in the head clearance or xe2x80x9cflying heightxe2x80x9d as the date storage device is operated. As recording density increases, recording heads must fly closer to the disc surface to maintain signal strength. Lower flying heights necessitate tighter tolerances on fly height variation to avoid head-disc interactions. Currently, target fly heights are achieved in part by precisely controlling the dimensions of the slider during the manufacturing process. In the future however, manufacturing limits may be reached, and methods for correcting slider fly characteristics after fabrication may be needed. Furthermore, reductions in the required fly height may require some form of active adjustment to maintain the spacing between the head and disc.
Various techniques have been proposed for changing slider geometry or orientation or for moving a portion of the slider in response to the head clearance during operation to control fly height. These techniques have limits in actuation frequency response due to the dynamic characteristics of the system since the recording head to disc spacing is coupled to the orientation of the slider and suspension. Furthermore, techniques that use an actuator located on the suspension or the slider must contend with the dynamics of any intervening components in order to change the pole tip spacing, thereby limiting overall performance.
A disc head slider is therefore desired which improves performance of mechanisms for actuating the pole tip spacing independently of the rest of the slider. Embodiments of the present invention provide solutions to these and other problems, and offer other advantages over the prior art.
One embodiment of the present invention is directed to a disc head slider having a disc-facing surface with a leading slider edge and a trailing slider edge. A primary bearing feature is formed on the disc-facing surface forward of the trailing slider edge and has a bearing surface. A plurality of pads is formed on the disc-facing surface between the primary bearing feature and the trailing slider edge. Each of the pads has an upper surface that is discrete from the upper surfaces of the other pads. An airflow barrier wall is positioned adjacent the plurality of pads to at least partially shield the plurality of pads from airflow from the primary bearing feature.
Another embodiment of the present invention is directed to a disc head slider having a slider body with a disc-facing surface and a trailing surface. A primary bearing feature is formed on the disc-facing surface and has a bearing surface. A piezoelectric microactuator is formed on the trailing surface of the slider body, which is changeable in shape in a direction normal to the disc-facing surface in response to an applied voltage. The microactuator has an upper surface which is recessed from the bearing surface. At least one raised pad is formed on the upper surface of the microactuator. Further features are provided for limiting pressurization of the at least one pad due to airflow from the primary bearing feature.
Other features and benefits that characterize embodiments of the present invention will be apparent upon reading the following detailed description and review of the associated drawings.